Leak detector

ABSTRACT

Method and apparatus is provided for detecting leaks in plastic bottles and other containers. The device is capable of testing such containers for leaks without relying upon an outside source of air to pressurize the container being tested and can do so at a faster rate than was heretofore possible. Pressured fluid is introduced into the bottle or other container to be tested from a self-contained unit. A pressure switch having a diaphragm type valve is used to detect the presence of a leak. Upon pressurizing the container or as part of the pressurizing step, means are actuated tending to urge the pressured fluid from the bottle thereby speeding up the testing process. Additionally, the present device checks a bottle for the accuracy of its neck or finish portion.

United States Patent Harris [541 LEAK DETECTOR [72] Inventor: David S.Harris, 3118 Heatherdowns Blvd, Toledo, Ohio 43614 [22] Filed: June 22,1970 [21] Appl. No.: 48,320

[51] Int. Cl. ..G0lm 3/32 [58] Field of Search ..73/49.2, 41, 45, 45.1,45.2, 73/453, 37

[56] References Cited UNITED STATES PATENTS I 3,496,761 2/1970 Powers,Jr. ..73/45.2 2,084,653 6/1937 Preston ..73/45.l X

Primary Examiner-Louis R1 Prince Assistant Examiner-William A. Henry, llAttorney-Philip M. Rice and E. J. Holler 1 Aug. 15, 1972 [571 ABSTRACTMethod and apparatus is provided for detecting leaks in plastic bottlesand other containers. The device is capable of testing such containersfor leaks without relying upon an outside source of air to pressurizethe container being tested and can do so at a faster rate than washeretofore possible. Pressured fluid is in troduced into the bottle orother container to be tested from a self-contained unit. A pressureswitch having a diaphragm type valve is used to detect the presence of aleak. Upon pressurizing the container or as part of the pressurizingstep, means are actuated tending to urge the pressured fluid from thebottle thereby speeding up the testing process. Additionally, thepresent device checks a bottle for the accuracy of its neck or finishportion.

16 Claims, 8 Drawing Figures PATENTEDAUG 15 e972 SHEET' 1 0F 6 INVENTOR.[3mm 8 Hams @MMQQ PATENTEDAUE 15 I972 SHEET 2 OF 6 PATENTEDMI 1 5 mm3.683; 6?? sum 3 or 5 F I G 3 INVENTOR.

DAWDQHAIQRR BY -c-z AWORMQQS LEAK DETECTOR BACKGROUND OF THE INVENTIONIn the forming of plastic bottles, problems are frequently encounteredby the presence of minute pin holes in the bottles. Although not readilydiscernible to the eye, the presence of such pin holes is reason forrejecting the bottle.

Accordingly, it is necessary that plastic bottles be tested to determinewhether such bottles have pin holes which would present problems if thebottle were used for packaging goods. The bottles are customarily testedby introducing therein fluid pressure from an outside source and waitinga period of time to see whether such pressure is lost through leakage.The prior art devices have been fairly expensive and have generallyrequired a source of compressed air or similar medium for introducingpressure into the bottle to be tested. Such prior art devices have beencumbersome to operate and have required excessive amounts of time totest individual bottles. Other prior art devices rely on measuringmechanical vibrations produced when a bottle subjected to fluid pressureleaks. Such device is described in US. Pat. No. 3,224,252.

Although not necessarily so limited in its application, the improvementfeature of the present invention may be used in a leak detector of thetype disclosed in application Ser. No. 866,409, filed Aug. 29, 1969,which is assigned to the assignee of the present application.

It is an object of the present invention to provide a new and economicaldevice for leak testing plastic bottles.

It is another object of the present invention to provide a leak detectorwhich is completely self-contained and does not require an outsidepressure source.

It is a further object of the present invention to provide a method andapparatus for testing plastic bottles for leaks which is faster thanthose previously known and yet which is extremely accurate.

Finally, it is an object of the present invention to provide a methodand apparatus for checking the neck or finish portion of a container andfor rejecting those in which such portion is either too high or too low.

Other objects and advantages of the present invention will becomereadily apparent from the following detailed description taken inconjunction with the annexed sheets of drawings on which:

FIG. 1 is a perspective view illustrating the apparatus of the presentinvention.

FIG. 2 is an end elevational view thereof.

FIG. 3 is a view similar to FIG. 2 showing the apparatus moved to aposition at which the neck grasping mechanism has engaged the bottle tobe tested prepara' tory to lifting.

FIG. 4 is a view similar to FIG. 3 showing the apparatus after liftingand introducing pressure into the bottle.

FIG. 5 is an enlarged view of the sealing head.

FIG. 6 is a schematic view showing the pneumatic and wiring connectionsof the leak detector.

FIGS. 7 and 8 are schematic views showing the pressure switch portion ofthe leak detector.

Referring now to the drawings, there is provided a conveyor belt 10 onany suitable support mechanism 11 for conveying bottles B to the testingstation. Positioned above the conveyor 10 is a leak tester generallydesignated by the numeral supported on guide rods 21 extending upwardlyfrom a frame 22. Secured to the tops of the respective guide rods 21 isa stationary platform 23 having mounted thereon a fluid pressurecylinder 24 having a piston rod 28 extending therefrom. Mounted on theguide rods 21 in slideable relationship thereto is a movable platform 25to which the free end of the piston rod 28 is connected. Thus, actuationof the fluid pressure cylinder 24 to extend or retract the piston rod 28serves'to raise or lower the platform 25. Secured to the rods 21 is asupport member 27 on which is supported an electric eye mechanism 8 fordetecting the movement of successive bottles into position for testing.

The movable platform 25 has a pair of cams 34 mounted thereon. Each ofthe cams has a first vertical face 35, a second face 36 extendingdownwardly and inwardly therefrom and a third face 37 extendingvertically downwardly from the second face 36. The function of the earns34 will become apparent shortly.

It has been determined that maximum accuracy is obtained if the plasticbottle being tested is out of contact with any support members whichwould tend to deform the thin, flexible wall thereof. Accordingly, meansare provided for supporting the bottles at the relatively rigid neckportions thereof. Such means include a'neck grasping mechanism indicatedgenerally by the numeral 40.

The neck grasping mechanism includes a pair of support blocks 41 mountedon the lower end of a pair of rods 32. The rods 32 extend upwardlythrough the stationary platform 23' in a slideable relationshiptherewith. Such rods also pass through the movable platform 25 and theoutside portion of housings 31 mounted thereon and are maintained inslideable relationship therewith. The rods have nuts 33 secured theretowhich engage the stationary platform 23 when the blocks 41 are in theirlowermost position as illustrated in FIG. 2. Thus, the nuts 33 serve tolimit the lowermost position of the support blocks 41.

Mounted on the movable platform 25 and contained in the housings 31 area pair of compression springs 30 which serve to urge the support blocks41 and the movable platform 25 apart. Thus, when the movable platform 25is at its lower most position and during its initial movement upward thesprings 30 serve to temporarily hold the support blocks 41 in astationary position at their lower most position. Upward movement of thesupport blocks 41 is effected by means of collars 33a secured to therods 32. Thus, when the movable platform 25 has been raised to aposition where the collars 33a are contacted by the tops of therespective housings 31 (FIG. 3), any continued upward movement of suchplatform will carry with it the support blocks 41.

The support blocks 41 are L-shaped, having vertical legs 84 andhorizontal legs 85. Each of the horizontal legs 85 has an abutment 86(FIGS. 1 and 5) forming its innermost portion.

Each support block 41 has an aperture 42 for slideably receiving amovable pin 43. Each of the pins has a cam engaging wheel 44 mounted onone end and a neck gripping yoke 45 mounted on the other end. Acompression spring 46 encircles each of the pins 43 and serves to urgethe cam engaging wheels 44 against the respective earns 34. It can bereadily seen from viewing the drawings that the neck gripping yokes 45are moved from a position out of engagement with the neck of the bottleB (FIG. 2) to a position in. engagement with the neck of bottle B (FIG.3) by actuating the fluid pressure cylinder 24 to lift the movableplatform 25 and thereby'move the cams 34 relative to the cam engagingwheels 44. As the cam engaging wheels 44 engage the downwardly andinwardly inclined faces 36 of the respective cams 34, the pins 43 areurged inwardly to cause the neck gripping yokes 45 to engage the neck ofthe bottle B. Continued upward movement of the movable platform 25 bymeans of the fluid pressure cylinder 24 causes respective housings 31thereof to engage the collars 33a and then to lift the closed neckgrasping mechanism 40 and the engaged bottle B as showing in FIG. 4.

Extending downwardly from the stationary platform 23 in axial alignmentwith the neck of a bottle held by the gripping yokes 45 is a rod 53having a sealing head 51 mounted on the lower end thereof. The sealinghead has a plug gage 51a extending from the lower end, the purpose ofwhich will be described later. The rod 53 is slideable with respect tostationary platform 23 and is yieldingly urged downwardly by acompression spring 50 positioned between it and the upper end of thesealing head 51. A nut 54 secured to threads at the free end of the rod'53 serves to determine the lowermost position of the rod 53 and, henceof the sealing head 51. A passageway 52 for directing air into thebottle extends through the rod 53, the sealing head 51 and the plug gage51a.

It can be readily seen that the sealing head 51 is free floating and ispositioned for engagement by the top rim of the bottle B being tested asit is lifted by the neck grasping mechanism 40. As the bottle B and theneck grasping mechanism 40 continue to be lifted, the sealing head isurged upwardly.

The sealing head serves a dual function in that it normally serves asthe conduit through which air is directed into the bottle and, yet, incombination with the neck grasping mechanism 40 prevents a pressurebuild-up in a bottle if the neck portion thereof is shorter thanspecified or if an obstruction due to flash is present on the inside ofthe neck. Before describing the means for pressurizing the bottles, thislatter feature will be described.

Referring to FIG. 5, the sealing head 51 has a rubber sealing pad 89 atits lower end immediately above the plug gage 51a and a threadedsidewall 90 to which is engaged a threaded knob 91. The threaded knobhas an abutment 92 which extends radially outwardly to a positionoverlying the abutrnents 86 of the respective support blocks 41. Whenthe neck grasping mechanism 40 and the engaged bottle B are raised,contact will be made with the sealing head 51. If the neck of the bottleB is equal to or greater than the height specified as being withintolerance, such contact will be between the top rim of the bottle B andthe sealing pad 89. If the neck is less than the height specified, theabutrnents 86 of support blocks 41 will contact the abutment 92 ofthreaded knob 91 thus keeping the rim out of sealing contact with thesealing pad 89 and preventing a build up of pressure in the bottle B. Asis apparent, the mechanism may be adjusted to check the neck heights ofbottles having different specified heights simply by rotating thethreaded knob 91 to raise or lower it on the sealing head 51.

Irrespective of the neck height, if the interior of the neck has anobstruction, for example as caused by unwanted flash, the plug gage willstrike it and prevent the rim from sealingly engaging the sealing pad89. The plug gage is somewhat smaller than the normal inside diameter ofthe neck and will, therefore, fit readily in such neck opening unless anobstruction is present.

The means for supplying air to the passageway 52 for pressuring thebottle includes a pair of collapsible rubber bulbs 55 mounted on thestationary platform 23 and a pair of upstanding studs having enlargedheads 103 in alignment therewith. As can be seen from FIGS. 1 and 4,continued upward movement of the movable platform 25 after engagement ofthe enlarged heads 103 against the bulbs 55 collapses the bulbs andexpels air therefrom into tubes 56 connected between them and a coupling58 connected to the rod 53. The positioning of the respective parts issuch that unless the bottle being tested has a low neck or anobstruction as described above, it is sealingly engaged'to the sealingpad 89 during collapse of the bulbs causing the air expelled during suchcollapse to flow through the tubes 56, coupling 58, and passageway 52into the bottle B, thereby pressurizing the bottle. The pressure in thebottle is rather small, on the order of one to two inches water.

The apparatus of the present invention is also capable of detecting andrejecting bottles in which the neck is too high. As previously noted, ifthe neck is equal to or greater than the height specified as beingwithin tolerance, the top rim of the bottle B will contact the sealingpad. In this case, the sealing head 51 is urged upwardly overcoming theresistance of the compression spring 50 solely by the rim pushingagainst the sealing pad 89. Therefore, the height to which the sealinghead is pushed will be determined solely by the height of the neck.

Mounted on the coupling 58 is a normally closed valve 135 having anupwardly extending peg 136. The valve is opened to atmosphere bydepressing the peg 136. Positioned directly above the peg 136 is athreaded stud 137 supported on brackets 138mounted on the stationaryplatform 23. The height of the threaded stud is adjustable so that thepeg 136 will contact it only if the neck of the bottle B is greater thanthe specified height tolerance. If the neck exceeds such tolerance, therod 53 will be urged upwardly to a position at which the peg 136 willengage and be depressed by the stud 137 thereby opening the valve 135.Such opening prevents a build up of pressure in the bottle and indicatesthat the bottle is defective.

Connected to the rod 53 and tied in to the passageway 52 is a secondtube connected through a pressure relief switch 110 (FIG. 6) to aconventional pressure sensing mechanism designated generally by thenumeral 71. An auxiliary tube 70a leads from the switch 110 to a dialgauge 111 on which the pressure in the bottle can be visually read. Thepressure sensing mechanism 71 may be a Hays pressure switch, Model No.212--0l-C, having a range of 0-10 inch water column manufactured by Thel-Iays Corporation, Michigan City, Indiana. The mechanism includes apressure switch 72 having a resilient diaphragm 73. The pressure switch72 communicates with the tube 70 leading to one side of the diaphragmand communicates, on the other side of the diaphragm, with atmosphere,as by an aperture 74. Extending outwardly from the pressure switch 72 isan arm 75 having an enlarged head 76. Any suitable switch 77 such as areed switch or magnetic switch is positioned slightly to one side of theenlarged head 76. The switch is to the left of the enlarged head 76 asviewed in FIG. 6 and to the right as viewed in FIGS. 7 and 8. Theenlarged head is normally urged out of contact with the switch 77 by aspring 61 secured between arm 75 and the free end of an arm 61aextending from a fixed block 60. The block 60 is mounted on anysupporting means (not shown) and includes a set screw 60a which servesto pivot the arm 61a and adjust the tension on the spring 61. The spring61 urges the-arm 75 against an adjustable stop 710 where it is normallypositioned during the at rest interval between bottles being tested.

As is well known, the arm 75 and diaphragm 73 of the Hays pressureswitch 72 are so interconnected that movement of the diaphragm 73 in onedirection causes the arm 75 to move in the opposite direction and viceversa. Thus, as may be seen in FIGS. 7 and 8, the Hays pressure switchis in an at rest position with the arm 75 being urged to the leftagainst the adjustable stop 71a and the diaphragm 73 being deflected orbulged to the right. When pressure is introduced into the bottle B beingtested and, hence, into the pressure switch 72, the diaphragm 73 isurged in the same direction. However, it is not deflected furtherbecause the adjustable stop 61a prevents further movement of the arm 75to the left as viewed in FIGS. 7 and 8.

A fluid pressure cylinder 62 is provided to attempt to draw the arm 75toward the switch 77 immediately following the step of pressurizing thebottle. A rod 62a extending from the forward end of cylinder 62 is setto retract a constant distance upon the introduction of pressured fluidto the forward end thereof. The rod 62a is connected to a spring 69which in turn is secured to the arm 75. Thus, the force acting to pullthe arm 75 toward the switch 77 depends on strength of the spring 69.

The movement of the arm 75 caused by retraction of the rod 62a urges thediaphragm in the opposite direction creating a rapid build-up ofpressure in the bottle being tested. Such build-up of pressure tends toexpel air from the bottle through any pin holes present much faster thanwould otherwise occur. If the bottle B is defective, the leakage willresult in a sufficient pressure loss during the period the rod 62a isretracted that the arm 75 will be drawn to an extreme position at whichthe head 76 closes the switch 77. If the bottle B is satisfactory, thepressure contained therein will sucgauge 111.

In testing bottles of different volumes, it is necessary to adjust thelength of arm 75 movement needed to actuate the switch 77. Thus, ashorter arm movement should be required to'reject a small bottle than toreject a large bottle because a small bottle willhave a greater pressurebuild-up per given length of arm 75 movement than a large bottle. Thelength of arm movement needed to actuate the switch may change by movingthe adjustable stop 71a which determines the at rest position of thearm.

If a switch relying on proximity rather than actual contact of the head76 is used for the switch 77, it will be desirable to provide a stop 71bto limit movement of the arm 75 theretoward. Thus, if a reed type switchhaving a glass housing is used, contact between the head and the switchshould be avoided to prevent breakage of the glass.

If desired, other means may be used to create a pressure build-up in thebottle being tested. Such means include a pair of pads 150 on the freeend of rods 151 extending from fluid pressure cylinders 152. (See FIGS.4 and 6). The cylinders 151 are mounted on the respective guide rods 21so that the pads 150 are on opposite sides of the bottle B being tested.Extension of the rods 151 causes the pads 150 to engage and thenpartially collapse the bottle B thereby increasing the pressure therein,as shown in phantom lines in FIG. 4.

A better understanding of the invention will be gained from a review ofthe pneumatic and wiring connections for testing the bottles B anddisposing of the rejects which are shown schematically in FIGS. 6 and 7.Referring to FIGS. 1 and 6, it should initially be noted that the lines,70 and 70a do not form part of the pneumatic system but rather servesimply as conduits for directing air from the collapsible rubber bulbs55 to the bottle B and to the pressure switch 72 and dial The pneumaticsystem includes a main air line 120 connected to a source of compressedair (not shown). The main air line 120 is connected to supply air to l avalve 121 controlling the flow of air to the fluid pressure cylinder 24connected to the stationary platform 23, (2) four solenoid valves A, B,C and D, and (3) a pressure relief valve 122. The connection to solenoidvalve D is through tap line 120a.

The valve 121 functions to direct air to the front or v back of cylinder24 through lines 123 and 124 dependcessfully resist the force of thespring 69 caused by retraction of the rod 62a and will prevent movementof the enlarged head 76 to a position causing actuation of the switch.

The length of time the arm is retracted is determined by a timer notshown. Although the length of time may be varied to detect various sizeholes, it has been determined that holes of 0.010 inch can be detectedin less than one-half ()6) second after the bottle is pressurized and atspeeds approaching two-tenths (0.2) second. Holes of 0.005 inch havebeen detected in one second.

ing on whether the cylinder 24 is to raise or lower the movable platform25. The valve is a diaphragm type controlled by the presence or absenceof air pressure directed to the top thereof through line 125 which inturn is controlled by the solenoid A. Initial actuation of the solenoidA results from an. electrical impulse directed thereto from the electriceye 8 upon detecting the presence of a bottle to be tested. The openingof the solenoid valve A permits pressuredl air to flow from the main airline through the line to depress the diaphragm in valve 121. Suchdepression of the diaphragm directs air introduced into the valve 121from the main air line 120 to flow to the line 123 con nected to theforward or lower end of cylinder 24 thereby retracting the piston rod 28and raising the movable platform 25. When the solenoid valve A is closedand no air is directed through line 125, the diaphragm is relaxedcausing air introduced into the valve 121 from the main air line 120 toflow through line 124 connected to the rear or upper end cylinder 24thereby lowering the movable platform 25. The valve 121 is provided witha vent 121a to permit the diaphragm to relax upon closing the solenoidvalve A.

The solenoid valve B is electrically connected to a switch 80 and uponactuation thereby opens to direct air from the main air line 120 throughline 66 connected to the forward end of fluid pressure cylinder 62 tothereby retract the rod 62a. The switch 80 is mounted on a supportmember 67 extending upwardly from stationary platform 23 and has aplunger 81 extending downwardly therefrom. Mounted on the upper movableplatform 25 in alignment with the plunger 81 is an upright post 82.Theheight of the post 82 is such that it depresses the plunger 81 as themovable platform 25 reaches its uppermost position and as the rubberbulbs 55 complete the introducing of air into the bottle B. Depressionof the plunger 81 energizes the switch 80 causing a signal to betransmitted to the solenoid valve B, opening it and permitting pressuredfluid to flow to the forward end of the cylinder 62, thereby retractingthe rod 62a and stretching the spring 69. The tension caused bystretching the spring tends to urge the arm 75 toward the reed switch77. As previously noted, if the bottle is satisfactory, the tendency tomove the arm 75 toward the switch 77 will be successfully resisted bythe pressure on the opposite side of the diaphragm 73 and the head 76will remain out of contact of the switch 77. If the bottle is defective,air will be expelled therefrom, reducing the pressure therein, and thuspermitting the head 76 to move to a position at which it actuates theswitch 77. Such actuation will occur regardless of whether the defect isdue to pin holes in the bottle or out of tolerance neck portions. Thepoint is that any defect which prevents retention of pressure will bedetected and result in rejection of the bottle.

The solenoid valve C is electrically connected to the magnetic switch77. Actuation of the solenoid valve C will result when a defectivebottle B permits the enlarged head 76 to contact the switch 77. Suchactuation opens the solenoid valve C to direct air from the main airline 120 through line 128 leading to the rear end of a fluid pressurecylinder 129 mounted on the support mechanism 11. The cylinder 129 has arod 130 to which is connected a kicker bar 131. Thus, air introducedthrough the line 128 will serve to extend the rod 130 and knock thedefective bottle from the conveyor 10. The solenoid C is provided with atime delay mechanism which delays actuation of cylinder 129 until thedefective bottle to be removed has been released by the neck grippingyokes 45.

Solenoid valve D is provided when it is desired to use the pads 150squeezing the bottle B being tested to build up pressure therein. Suchpads can be used either in place of the collapsible bulbs 55 or as asupplement thereto. The solenoid valve D is actuated by the same switch80 that actuates solenoid valve B upon raising of the movable platform25 to its uppermost position. Such actuation opens the solenoid valve Dand permits pressured air to flow therethrough from line 120a to line155 to the rear ends of the respective cylinders 152 extending the rodsthereof and thus moving the pads 150 to a position which partiallycollapses the bottle B as shown in phantom lines in FIGv 4.

For some applications, in lieu of using the pads 150 to squeeze thebottles, it is desirable to move them to a position where they willlightly contact opposite sides of such bottles. This positioning of thepads 150 is especially desirable when testing bottles having flatsidewall portions which would otherwise be subject to bulging. When thepads 150 are moved only to a position of light contact, the solenoid Dmay be connected for actuation by the electric eye 8 so that the pads150 will contact the bottle B as it is moved upwardly.

It has also been determined that for some bottles, a sufficient pressurebuild-up for testing may be obtained simply from movement of thediaphragm 73. Under this modification, the collapsible bulbs 55 and theair lines 56 leading therefrom may be dispensed with. Thus, when themovable platform 25 reaches a position where the upright post 82depresses plunger 81 energizing switch 80 and, thus opening solenoidvalve B, the cylinder 62 will act to draw the arm 75 toward the switch77. Such movement of the arm 75 moves the diaphragm 73 in a direction(to the left in FIG. 7) expelling air through line and into the bottleB. If the bottle B is satisfactory, the rapid pressure build-up willprevent the arm from moving far enough for the enlarged head to contactthe switch 77 In order to obtain a sufiicient pressure build-up underthis modification, it is desirable to increase the distance throughwhich the arm 75 may travel by moving the adjustable stop 71a to itsextreme'left position as viewed in FIGS. 7 and 8.

The present invention which provides a positive means for attempting toexpel air from the bottle being tested permits a speedier detection ofthe defective bottles than heretofore known. The leak detector of thepresent invention can detect a 0.010 inch hole in a plastic bottle inless than one-half (B) second after pressurizing the bottle. Incontrast, testing apparatus of the type described in application Ser.No. 866,409, filed Aug. 29, l969 (assigned to the assignee of thepresent invention) requires approximately one second after pressurizingthe bottle to detect a 0.010 inch hole.

It can be seen from the foregoing that the present invention provides aneconomical and compact unit for the testing of plastic bottles for leaksresulting from small holes therein. Additionally, although utilizing theprinciple of pressure testing, it does not require an outside source ofair pressure. It permits high speed testing of bottles and, yet, isextremely reliable.

Several modifications will become readily apparent to those skilled inthe art.

I claim:

1. Apparatus for leak testing a hollow article having a neck portiondefining an opening comprising a. a support member for supporting thearticle to be tested,

b. a test head positioned over said support member, said test headhaving sealing means to isolate the interior of said article fromatmosphere,

c. means yieldably supporting said test head for movement along the axisof said neck portion from a normal lower position to an upper position,

(1. means engagable with said neck portion for moving said article intoengagement with said test head and for continuing said movement to urgesaid test head upwardly,

e. means responsive to said movement for introducing pressure into saidarticle,

test head has a plug gauge sized to fit within the opening of said neckto permit sealing engagement between the test head and an article havinga neck opening within a specified tolerance and to prevent sealingengagement between the test head and an article having a neck openingoutside said tolerance.

means for introducing pressure in the article comprises means forpartially collapsing said article.

neck portion defining an opening comprising,

f. a pressure switch having a variable volume chamber communicating withthe interior of said article, said pressure switch operable to detectthe loss of pressure therein through means actuated by a predeterminedamount of contraction in said chamber,

and g. means for attempting to contract said chamber.

2. The apparatus as defined in claim 1 wherein said 3. The apparatus asdefined in claim 1 further including means to prevent sealing engagementbetween the test head and the article being tested when said neckportion is shorter than specified.

4. The apparatus as defined in claim 3 including first abutment meansassociated and axially movable with said neck engaging means and secondabutment means associated and axially movable with said test head, saidfirst and second abutment means being axially aligned and spaced apart apredetermined distance, said predetermined distance being directlyrelated to the specified height of said neck.

5. The apparatus as defined in claim 1 wherein the distance moved bysaid test head is determined by the height of said neck portion andfurther including pressure relief means operable to vent pressure fromthe article upon movement of the test head beyond a predetermineddistance.

6. The apparatus as defined in claim 1 wherein the 7. Apparatus for leaktestinga hollow article having a neck portion defining an openingcomprising a. a support member for supporting the article to be tested,

b. a test head positioned over said support member, said test headhaving sealing means to isolate the interior of said article fromatmosphere,

0. means yieldably supporting said test head for movement along the axisof said neck portion from a normal lower position to an upper position,

d. means engagable with said neck portion for moving said article intoengagement with said test head and for continuing said movement to urgesaid test head upwardly,

e. means responsive to said movement for introducing pressure into saidarticle,

and (f) means to prevent sealing engagement between the test head andthe article being tested when said neck portion is shorter thanspecified.

8. The apparatus as defined in claim 7 including first 9. Apparatus forleak testing a hollow article having a a. a support member forsupporting the article to be tested,

b. a test head positioned over said support member, said test headhaving sealing means to isolate the interior of said article fromatmosphere,

c. means yieldably supporting said test head for movement along the axisof said neck portion from a normal lower position to an upper position,

. means engagable with said neck portion for moving said article intoengagement with said test head and for continuing said movement to urgesaid test head against its yielding support means, the distance moved bysaid test head being determined in part by the height of said neckportion,

e. means responsive to said movement for introducing pressure into saidarticle,

and (f) pressure relief means operable to vent pressure from the articleupon movement of the test head beyond a predetermined distance.

10. In apparatus for leak testing .a hollow article having an openingincluding a. a support member for supporting the article to be tested,

b. a self-contained unit having a variable sized chamber for holding asupply of air,

c. means for sealing said opening,

d. means responsive to relative movement between said article and saidunit for reducing the size of said chamber and evacuating the airtherefrom,

e. communication means for directing air evacuated from said chamberinto said article to cause a pressure build-up therein,

f. a pressure switch communicating with the article for sensing the lossof pressure therein,

g. the improvement comprising means for creating a pressure surge withinthe article following said pressure build-up.

11. The apparatus as defined in claim 10 wherein the means for creatinga pressure surge within the article comprises an expansible chamber inthe pressure switch and means for contracting said chamber.

12. Apparatus for leak testing a hollow article comprising (a) means forsealing said article from atmosphere, (b) means for creating a'pressurewithin said sealed article, (c) pressure detecting means communicatingwith the interior of said article, the volume contained within thatportion of the system subjected to pressure following actuation of thepressure creating means being a fixed size, said volume being defined by(l) the interior of the article, (2) the pressure creating means, (3)the pressure detecting means, and (4) means causing communicationbetween (1), (2) and (3) above and ((1) means for reducing said volumeto increase said pressure.

13. Apparatus for leak testing a hollow article having a neck portiondefining an opening comprising a. a support member for supporting thearticle to be tested,

b. a test head positioned over said support member, said test headhaving sealing means to isolate the interior of said article fromatmosphere,

c. means for imparting relative movement between said test head and saidneck portion to bring them toward a position of engagement,

d. means for introducing pressure into said article,

and

e. means to prevent sealing engagement between the neck portion isshorter than specified.

14. The apparatus as defined in claim 13 further including meansengageable with said neck portion for supporting said neck portionduring engagement with said test head.

15. The apparatus as defined in claim 14 including first abutment meansmounted on said neck supporting means and second abutment means mountedon said test head, said first and second abutment means being axiallyaligned and spaced apart a predetermined distance, said predetermineddistance being directly related to the specified height of said neck.

16. Apparatus for leak testing a hollow article having a neck portiondefining an opening comprising,

a. a support member for supporting the article to be tested,

b. a test head positioned over said support member,

said test head having sealing means to isolate the interior of saidarticle from atmosphere,

0. means for engaging said neck portion at a predetermined positionabove said member,

support means for imparting relative movement between means forintroducing pressure into said article,

and

. pressure relief means operable to vent pressure from the article whenthe spacing between the means engageable with neck portion and the'testhead is greater than a predetermined distance.

1. Apparatus for leak testing a hollow article having a neck portiondefining an opening comprising a. a support member for supporting thearticle to be tested, b. a test head positioned over said supportmember, said test head having sealing means to isolate the interior ofsaid article from atmosphere, c. means yieldably supporting said testhead for movement along the axis of said neck portion from a normallower position to an upper position, d. means engagable with said neckportion for moving said article into engagement with said test head andfor continuing said movement to urge said test head upwardly, e. meansresponsive to said movement for introducing pressure into said article,f. a pressure switch having a variable volume chamber communicating withthe interior of said article, said pressure switch operable to detectthe loss of pressure therein through means actuated by a predeterminedamount of contraction in said chamber, and g. means for attempting tocontract said chamber.
 2. The apparatus as defined in claim 1 whereinsaid test head has a plug gauge sized to fit within the opening of saidneck to permit sealing engagement between the test head and an articlehaving a neck opening within a specified tolerance and to preventsealing engagement between the test head and an article having a neckopening outside said tolerance.
 3. The apparatus as defined in claim 1further including means to prevent sealing engagement between the testhead and the article being tested when said neck portion is shorter thanspecified.
 4. The apparatus as defined in claim 3 including firstabutment means associated and axially movable with said neck engagingmeans and second abutment means associated and axially movable with saidtest head, said first and second abutment means being axially alignedand spaced apart a predetermined distance, said predetermined distancebeing directly related to the specified height of said neck.
 5. Theapparatus as defined in claim 1 wherein the distance moved by said testhead is determined by the height of said neck portion and furtherincluding pressure relief means operable to vent pressure from thearticle upon movement of the test head beyond a predetermined distance.6. The apparatus as defined in claim 1 wherein the means for introducingpressure in the article comprises means for partially collapsing saidarticle.
 7. Apparatus for leak testing a hollow article having a neckportion defining an opening comprising a. a support member forsupporting the article to be tested, b. a test head positioned over saidsupport member, said test head having sealing means to isolate theinterior of said article from atmosphere, c. means yieldably supportingsaid test head for movement along the axis of said neck portion from anormal lower position to an upper position, d. means engagable with saidneck portion for moving said article into engagement with said test headand for continuing said movement to urge said test head upwardly, e.means responsive to said movement for introducing pressure into saidarticle, and (f) means to prevent sealing engagement between the testhead and the article being tested when said neck portion is shorter thanspecified.
 8. The apparatus as defined in claim 7 including firstabutment means associated and axially movable with said neck engagingmeans and second abutment means associated and axially movable with saidtest head, said first and second abutment means being axially alignedand spaced apart a predetermined distance said predetermined distancebeing directly related to the specified height of said neck. 9.Apparatus for leak testing a hollow article having a neck portiondefining an opening comprising, a. a support member for supporting thearticle to be tested, b. a test head positioned over said supportmember, said test head having sealing means to isolate the interior ofsaid article from atmosphere, c. means yieldably supporting said testhead for movement along the axis of said neck portion from a normallower position to an upper position, d. means engagable with said Neckportion for moving said article into engagement with said test head andfor continuing said movement to urge said test head against its yieldingsupport means, the distance moved by said test head being determined inpart by the height of said neck portion, e. means responsive to saidmovement for introducing pressure into said article, and (f) pressurerelief means operable to vent pressure from the article upon movement ofthe test head beyond a predetermined distance.
 10. In apparatus for leaktesting a hollow article having an opening including a. a support memberfor supporting the article to be tested, b. a self-contained unit havinga variable sized chamber for holding a supply of air, c. means forsealing said opening, d. means responsive to relative movement betweensaid article and said unit for reducing the size of said chamber andevacuating the air therefrom, e. communication means for directing airevacuated from said chamber into said article to cause a pressurebuild-up therein, f. a pressure switch communicating with the articlefor sensing the loss of pressure therein, g. the improvement comprisingmeans for creating a pressure surge within the article following saidpressure build-up.
 11. The apparatus as defined in claim 10 wherein themeans for creating a pressure surge within the article comprises anexpansible chamber in the pressure switch and means for contracting saidchamber.
 12. Apparatus for leak testing a hollow article comprising (a)means for sealing said article from atmosphere, (b) means for creating apressure within said sealed article, (c) pressure detecting meanscommunicating with the interior of said article, the volume containedwithin that portion of the system subjected to pressure followingactuation of the pressure creating means being a fixed size, said volumebeing defined by (1) the interior of the article, (2) the pressurecreating means, (3) the pressure detecting means, and (4) means causingcommunication between (1), (2) and (3) above and (d) means for reducingsaid volume to increase said pressure.
 13. Apparatus for leak testing ahollow article having a neck portion defining an opening comprising a. asupport member for supporting the article to be tested, b. a test headpositioned over said support member, said test head having sealing meansto isolate the interior of said article from atmosphere, c. means forimparting relative movement between said test head and said neck portionto bring them toward a position of engagement, d. means for introducingpressure into said article, and e. means to prevent sealing engagementbetween the test head and the article being tested when said neckportion is shorter than specified.
 14. The apparatus as defined in claim13 further including means engageable with said neck portion forsupporting said neck portion during engagement with said test head. 15.The apparatus as defined in claim 14 including first abutment meansmounted on said neck supporting means and second abutment means mountedon said test head, said first and second abutment means being axiallyaligned and spaced apart a predetermined distance, said predetermineddistance being directly related to the specified height of said neck.16. Apparatus for leak testing a hollow article having a neck portiondefining an opening comprising, a. a support member for supporting thearticle to be tested, b. a test head positioned over said supportmember, said test head having sealing means to isolate the interior ofsaid article from atmosphere, c. means for engaging said neck portion ata predetermined position above said support member, d. means forimparting relative movement between said test head and said neck portionto bring them into sealing engagement, the axial distance between saidmeans for engaging said neck portion and the test head when engaged withthe neck portion being determined by the height of said neck portion, e.means for introducing pressure into said article, and f. pressure reliefmeans operable to vent pressure from the article when the spacingbetween the means engageable with neck portion and the test head isgreater than a predetermined distance.